Three colours of black: seabird strandings in Belgium during the Tricolor incident

• Main Authors: Stienen, Eric, Haelters, J, Kerckhof, F, van Waeyenberge, Jeroen
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2004
• Subjects: /dk/atira/pure/thematic/inbo_th_00143; Damage management (management); Alca torda; Melanitta nigra; Razorbill; Uria aalge; uria
• Online Access: https://data.inbo.be/pureportal/en/publications/three-colours-of-black-seabird-strandings-in-belgium-during-the-tricolor-incident(69f86f8b-51dc-4b3f-a1fe-6b7591cd86bd).html

After a small amount of oil had leaked into the southern North Sea as a results of the collision between the oil tanker Vicky and the sunken car carrier Tricolor on 1 January 2003, 249 oiled birds (98% Guillemot Uria aalge and Razorbill Alca torda) were received at the Bird Rehabilitation Centre at Ostend, Belgium. Following a second larger oil spill during the salvage works of the Tricolor a few weeks later, in total 9,177 birds stranded at the Belgian coast during the period 23 January to 15 February. This time, virtually all birds were heavily oiled and more than half of the birds were still alive on arrival in Ostend. More than 90% of the victims were Guillemot and Razorbill; other species that accounted for more than 1% of the stranded birds were Great Crested Grebe Podiceps cristatus and Common Scoter Melanitta nigra. The birds stranded in three waves. A first peak in numbers (> 1,000 victims per day) occurred at 26 January and consisted of high proportions of Guillemots that managed to reach the coast alive despite unfavourable wind conditions. In the following weeks, the daily numbers of stranded birds were closely related to the prevailing wind conditions. The second and third peak in the number of strandings coincided with two periods of strong onshore winds. Changes in the species composition and the location where the birds were found are thought to reflect the movements of the oil slick perpendicular and parallel to the coastline, respectively. The proportion of Razorbills among the auks found during the incident greatly differed from that at sea and the proportion of dead birds was much higher among Razorbills than Guillemots. These differences can not be explained from differences in wintering areas. It is suggested that the third peak in strandings was at least partly related to a wreck among auks that was unrelated to the oil polluation.